After a glacial dam outburst destroyed homes in Alaska, a look at the risks of melting ice masses

After the destruction of homes in Alaska due to an outburst from a glacial dam, there’s a renewed focus on the dangers posed by melting ice formations.

For over ten years, residents in the capital of Alaska have experienced periodic glacial dam outbursts, including the recent one that damaged at least two homes during the weekend.

What made this latest flooding astonishing was the rapid movement of water. The rising Mendenhall River quickly ate away at the riverbanks, leading to home damage and causing some inhabitants to evacuate.

The discussion of glaciers and the resulting floods from bursting ice-and-snow dams raises several questions and concerns:

What Triggered Juneau’s Flooding?
The flooding originated from a part of the receding Mendenhall Glacier known as the Suicide Basin. This glacier behaves like a dam, trapping precipitation and melt from the nearby Suicide Glacier in the spring and summer. Eventually, the water breaks free, pouring into Mendenhall Lake and then down the Mendenhall River. Such phenomena have been happening in the region since 2011.

Is Climate Change Responsible?
While climate change is indeed causing glaciers to melt, the relationship between climate change and glacial outburst floods is complex. Even though smaller glaciers like the Suicide Glacier react faster to climate variations, the floods themselves are not directly related to climate change. They are simply a result of water filling a basin and subsequently draining, typically during summer.

How Rare Are These Floods?
These events are not uncommon and pose threats to around 15 million people worldwide. The unpredictability in the timing and severity of glacial dam outbursts remains a challenge.

What is the Dynamic Nature of Glaciers?
Glaciers are in a constant state of change. As the Mendenhall Glacier continues to recede, some floods may cease to happen, while new ones may begin to occur. This constant variation is part of the glacier’s natural evolution.

What Are the Consequences of Glaciers Melting?
Beyond the risk of floods, the melting of glaciers can impact water supplies, agriculture, tourism, and local ecosystems. Alaska’s vast glaciers are a significant draw for tourists, and their retreat could have broad implications. Moreover, the annual ice loss from Alaska’s glaciers is massive, with enough water to cover Texas with 4 inches (10 centimeters) of water, according to Christian Zimmerman, the director of the U.S. Geological Survey’s Alaska Science Center. Additionally, the retreating glaciers can have significant ecological impacts, including on vital salmon habitats, an area where further research is being sought.

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